Square balers are agricultural machines in which charges of crop material are fed into a bale-forming chamber and are compacted, typically by means of a reciprocating plunger. The bale-forming chamber usually includes a device for tying bales and a discharge outlet, for example connected to a discharge chute for gently lowering bales onto the field. During normal baling operation, tied bales are ejected from the baler through action of the plunger. However, there is often a need to remove a bale from the bale-forming chamber when normal discharge of the bales is not possible or desirable, e.g. at the end of a baling operation to remove remaining bales from the bale-forming chamber.
Auxiliary ejector systems for unloading bales from the baler, independently of the plunger reciprocation, are known in the art. Such an ejector system can comprise a shuttle assembly, mounted in a wall of the bale-forming chamber, comprising a frame that reciprocates in a direction parallel to the direction of movement of the bales in the bale-forming chamber and independently from the motion of the compacting plunger. Such frame typically has dogs projecting from it to engage with the bales, e.g. gripping the bale during forward strokes of the shuttle assembly, that is to say when it is moving towards the discharge outlet of the bale-forming chamber, and slipping relative to the bale, e.g. the underside thereof, during return strokes. In this way, the reciprocating movement of the shuttle assembly incrementally advances the bales out of the discharge outlet.
The ejector mechanism may be controllable to enable an operator to select whether to discharge only the last bale, nearest the discharge outlet, or both the last bale and the one before it. To achieve this, the dogs can be arranged on the shuttle assembly in a longitudinally extending series and at least some of the dogs may be controllable by the operator e.g. using a selector assembly, such as disclosed in EP0814951, so that the controlled dogs may be positioned either to extend into the bale-forming chamber or to be retracted from it.
In EP2108246, an ejector system is disclosed that furthermore does not require the operator to decide on which of the dogs to activate based on prior inspection of the position of the bales in the bale-forming chamber. This system comprises a first shuttle assembly with dogs to engage with the last bale and a second shuttle assembly, reciprocating independently of the first shuttle assembly, with dogs to engage with the next-to-last bale. It is a disadvantage of the ejector system of EP2108246 that it requires multiple actuators, one for a partial bale eject (i.e. where only the last bale is ejected, another bale remaining present in the bale-forming chamber), and another one for a full bale eject (i.e. where all bales are removed from the baler).